I personally think that responsible smartphone use should be learned and practiced, rather than outright banning them.
I think this shows that adults are terribly addicted to their devices and think if they can’t stop using them, children won’t either. They certainly can’t teach how to use phones responsibly if they can’t do it themselves. Unfortunately for children the result is an outright ban.
Smartphones are orders of magnitude more distracting than whatever existed before. Also, you can teach digital literacy all the while forbidding smartphone use outside of class, there is no real opposition there.